1. Field of the Invention
The present invention relates to an image forming apparatus that adopts an electrostatic recording process, an electrophotographic recording process, or the like.
2. Related Background Art
Hereinafter, there will be described how a fixing device of an image forming apparatus of this type is controlled.
When the power supply of a conventional color image forming apparatus (such as a copying machine or a printer) that adopts an electrostatic recording process, an electrophotographic recording process, or the like is turned on, electrical energization of a fixing heater is performed until a fixing device reaches a print startable temperature. When the temperature of the fixing device reaches a printable temperature, it becomes possible to perform a print operation and the electrical energization of the fixing heater is terminated. When the temperature of the fixing device falls below the printable temperature again, the electrical energization is performed once more.
Also, there is proposed an image forming apparatus that has a low-power mode with which if a state where no print job is inputted continues for a predetermined time period, the electrical energization of a fixing heater is continuously interrupted, thereby reducing power consumption in standby.
This image forming apparatus is constructed so that when the inputting of a print job is performed again under a state where the low-power mode is set, the electrical energization of the fixing heater is resumed and, when it is detected that the fixing temperature rises to the print startable temperature, a print operation is started.
In general, in many cases, an image forming apparatus that is used at an office or the like and is shared by many users is set so that the transition to the low-power mode is performed using a timer. Also, in many cases, if the image forming apparatus is used with low frequency, each time a print job is inputted, the fixing device is heated from a power-saving state to a standby state and then print is started.
In such a case, if a long time is taken by the fixing device to return to the standby state, a print waiting time is elongated, which hinders the working efficiency of users from increasing. In addition, there occurs a problem in that power consumed by the fixing device to return from the low-power mode to the standby state is increased because an electrical energization time of the fixing device is elongated.
An object of the present invention is to provide an image forming apparatus as will be described below. According to the present invention, there is provided an image forming apparatus, comprising:
a fixing unit that performs thermal fixation for a sheet on which a developer has been transferred; and
a controller that sets a temperature of the fixing unit at one of a first temperature for fixing a developer expressing a monochrome image on a sheet and a second temperature for fixing developers expressing a color image on a sheet,
wherein if a color page is contained in an image forming job, the controller sets the temperature of the fixing unit at the second temperature and starts the image forming job.